Medical valve with positive flow characteristics

ABSTRACT

A medical valve device for use in selectively establishing a fluid flow between first and second medical implements is disclosed. The valve has a body defining a passage from a first port to a second port. The valve defines a first fluid volume when both medical implements are connected thereto, and a second, smaller volume when one of the implements is disconnected, thereby causing a positive flow of fluid from the valve to the second medical implement when the first implement is disconnected.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. Patent applicationSer. No. 09/078,941 filed May 14, 1998, which is a continuation-in-partof U.S. Patent application Ser. No. 08/767,587 filed Dec. 16, 1996.

FIELD OF THE INVENTION

[0002] This invention relates generally to a medical valve, and inparticular to a valve which, when connected between a first medicalimplement, such as a fluid source, and a second medical implement, suchas a catheter, facilitates fluid flow therebetween, and when the firstmedical implement is disconnected therefrom, induces a positive flow offluid through the valve in the direction of the second medicalimplement.

BACKGROUND OF THE INVENTION

[0003] The manipulation of fluids for parenteral administration inhospitals and medical settings routinely involves the use of connectorsand valves for selectively facilitating the movement of fluids betweentwo points. These valves are typically placed along a fluid flow lineleading to a patient or other destination. For example, the tube maylead to a catheter having its tip positioned within a patient.

[0004] The valve is arranged so that a fluid source or other line may beconnected thereto for providing a fluid flow from the source to thepatient. When the fluid source or line is removed, the valve closes,sealing the line leading to the patient.

[0005] The element which is connected to the valve may comprise a tubeor other medical implement such as a conduit, syringe, IV set (bothperipheral and central lines), piggyback line, or similar componentwhich is adapted for connection to the medical valve. Unfortunately,prior art valves suffer from a problem arising from the disconnection ofthese medical implements from the valve.

[0006] These valves define a space within them through which a fluid orother material may flow from the implement to the line on which thevalve is mounted. When the medical implement is connected to the valve,it typically occupies a portion of this internal valve space, displacingthe fluid (whether it be a liquid or air) within the valve.

[0007] A problem arises when the medical implement is disconnected fromthe valve. When the implement is disconnected, it no longer occupies aportion of the space in the valve. The increase in space within thevalve results in the fluid in the valve and line to which the valve isconnected moving to fill the space. In effect, the removal of theimplement creates a suction force which draws fluid into the valve.

[0008] In the medical setting, this movement of fluid is veryundesirable. When the valve is connected to a fluid line leading to apatient, the movement of fluid through the line towards the space in thevalve has the effect of drawing blood from the patient in the directionof the valve. A serious problem may result in that this blood may clotand clog the catheter near its tip, rendering it inoperable, and mayeven result in a clot of blood in the patient, which may prove fatal.

[0009] One attempt at overcoming this clogging problem has been to coatthe inner surface of the catheter near its tip in order to prevent bloodfrom sticking to its interior surfaces. This method has generally beenunsuccessful in preventing clogging of the catheter.

[0010] The risk of blood clogging of the catheter is significantlyheightened where the inner diameter of the catheter is small (e.g., 27gauge). These small catheters have the advantage, however, that theyreduce the trauma and discomfort caused by insertion into a patient.Because these catheters have a very small passage therethrough, even asmall suction force may draw sufficient amount of fluid back through acatheter toward the valve to introduce blood into the catheter tip,which blood may clog the catheter's passage.

[0011] Overcoming the above-stated problem is made more difficult whenconsidering other criteria which the valve must satisfy. For example,the valve should be arranged to so that it does not have any fluidstagnation points. If the fluid is allowed to stagnate in one or moreareas of the valve, bacteria growth and other problems may occur.

[0012] In addition, the valve should have an internal flow path which issmooth. Sharp edges and corners may damage blood cells and causehemolysis.

[0013] A valve which overcomes the above-stated problems is desired.

SUMMARY OF THE INVENTION

[0014] In accordance with the present invention there is provided avalve which is advantageously utilized between two medical implements.The valve of this invention has several features, no single one of whichis solely responsible for its desirable attributes.

[0015] Most importantly, the valve is arranged to provide a positiveflow (i.e. the movement of fluid in the direction out of the valve asopposed to into the valve) when one of the medical implements isdisconnected therefrom. At the same time, the valve is safe, reliableand capable of being used repeatedly, is simple to manufacture and use,and is suitable for high pressure applications.

[0016] The valve of the present invention is particularly suited to usein an application where one of the medical implements comprises acatheter having its tip positioned in a patient. In a preferredembodiment the second medical implement comprises a fluid source havinga connector for connection to the valve.

[0017] The valve of the present invention has a fluid space whichexpands upon connection of the second medical implement and contractsupon disconnection of the medical implement. When the valve is connectedto a catheter, disconnection of the second medical implement creates apositive flow from the valve to the catheter tip upon disconnection ofthe medical implement to avoid the potential problems of blood-clogging.The valve is particularly suited for applications with a catheter whereit is desirable to avoid negative flow, but may be used for otherapplications as well.

[0018] Preferably, the valve includes a housing adapted for connectionto a first medical implement and a second medical implement. The valvedefines a fluid space therein, and includes means for increasing thefluid space when the second medical implement is connected, and fordecreasing the fluid space when the second medical implement isdisconnected. Means are also preferably provided for defining a fluidpath through the valve when both medical implements are connectedthereto, and for closing the fluid path when the second medicalimplement is disconnected.

[0019] Further objections, features and advantages of the presentinvention over the prior art will become apparent from the detaileddescription of the drawings which follows, when considered with theattached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 illustrates a valve in accordance with the presentinvention as used to selectively provide fluid from a fluid sourceconnected to a fluid line leading to a catheter which is inserted into apatient;

[0021]FIG. 2 is a plan view of a housing of the valve in accordance witha first embodiment of the present invention;

[0022]FIG. 3 is a top view of the housing illustrated in FIG. 2;

[0023]FIG. 4 is a side view of the housing illustrated in FIG. 2;

[0024]FIG. 5 is an end view of the housing illustrated in FIG. 2;

[0025]FIG. 6 is a cross-sectional side view of the housing illustratedin FIG. 2 and taken along line 6-6 therein;

[0026]FIG. 7 is a perspective view of the valve in accordance with thefirst embodiment of the present invention;

[0027]FIG. 8 is a top view of the valve illustrated in FIG. 7;

[0028]FIG. 9 is a first end view of the valve illustrated in FIG. 7;

[0029]FIG. 10 is an opposite end view of the valve illustrated in FIG.9;

[0030]FIG. 11 is a cross-sectional view of the valve illustrated in FIG.7, taken along line 11-11 therein, illustrating a piston of the valve inan uncompressed position;

[0031]FIG. 12 is a cross-sectional view of the valve as illustrated inFIG. 11, with the piston in a second or compressed position utilizingthe tip of a medical implement;

[0032]FIG. 13 is a perspective view of the piston of the valve of thefirst embodiment of the present invention;

[0033]FIG. 14 is a top view of the piston illustrated in FIG. 13;

[0034]FIG. 15 is a side view of the piston illustrated in FIG. 13;

[0035]FIG. 16 is a cross-sectional side view of the piston illustratedin FIG. 14, taken along line 16-16 therein;

[0036]FIG. 17 is an end view of the piston illustrated in FIG. 14;

[0037]FIG. 18 is a cross-sectional side view of a valve in accordancewith a second embodiment of the present invention, illustrating a pistonof the valve in a first position;

[0038]FIG. 19 is a cross-sectional side view of the valve as illustratedin FIG. 18, with the piston in a second position;

[0039]FIG. 20 is a cross-sectional side view of a valve in accordancewith a third embodiment of the present invention, illustrating a pistonof the valve in a first position;

[0040]FIG. 21 is a cross-sectional side view of the valve as illustratedin FIG. 20, with the piston in a second position;

[0041]FIG. 22 is a cross-sectional side view of a valve in accordancewith a fourth embodiment of the present invention, illustrating a pistonof the valve in a first position;

[0042]FIG. 23 is a cross-sectional side view of the valve as illustratedin FIG. 22, with the piston in a second position;

[0043]FIG. 24 is a cross-sectional side view of a valve in accordancewith a fifth embodiment of the present invention, illustrating a pair ofpistons of the valve in a first position;

[0044]FIG. 25 is a cross-sectional side view of the valve as illustratedin FIG. 24, with the pistons in a second position;

[0045]FIG. 26 is a cross-sectional side view of a valve in accordancewith a sixth embodiment of the present invention, illustrating a pistonof the valve in a first position;

[0046]FIG. 27 is a cross-sectional side view of the valve as illustratedin FIG. 26, with the piston in a second position;

[0047]FIG. 28 is a cross-sectional side view of a valve in accordancewith a seventh embodiment of the present invention, illustrating apiston of the valve in a first position;

[0048]FIG. 29 is a cross-sectional side view of the valve as illustratedin FIG. 28, with the piston in a second position;

[0049]FIG. 30 is a cross-sectional side view of a valve in accordancewith a eighth embodiment of the present invention, illustrating aresilient element of the valve in a first position;

[0050]FIG. 31 is a cross-sectional side view of the valve as illustratedin FIG. 30, with the element in a second position;

[0051]FIG. 32 is a cross-sectional side view of a valve in accordancewith a ninth embodiment of the present invention, illustrating a seal ofthe valve in a first position;

[0052]FIG. 33 is a cross-sectional side view of the valve as illustratedin FIG. 32, with the seal in a second position;

[0053]FIG. 34 is a cross-sectional side view of a valve in accordancewith a tenth embodiment of the present invention, illustrating adiaphragm of the valve in a first position;

[0054]FIG. 35 is a cross-sectional side view of the valve as illustratedin FIG. 34, with the diaphragm in a second position;

[0055]FIG. 36 is a perspective view of a valve in accordance with aneleventh embodiment of the present invention;

[0056]FIG. 37 is a top view of the valve illustrated in FIG. 36;

[0057]FIG. 38 is a cross-sectional view of the valve illustrated in FIG.37 taken along line 38-38 therein and illustrating a piston of the valvein a first position;

[0058]FIG. 39 is a cross-sectional view of the valve illustrated in FIG.37 taken along line 39-39 therein and illustrating the piston of thevalve in a second position;

[0059]FIG. 40 is a perspective view of a housing of the valveillustrated in FIG. 36;

[0060]FIG. 41 is a top view of the housing illustrated in FIG. 40;

[0061]FIG. 42 is a cross-sectional view of the housing illustrated inFIG. 41 taken along line 42-42 therein;

[0062]FIG. 43 is a cross-sectional view of the housing illustrated inFIG. 41 taken along line 43-43 therein;

[0063]FIG. 44 is a perspective view of the piston of the valve;

[0064]FIG. 45 is a top view of the piston illustrated in FIG. 44;

[0065]FIG. 46 is a side view of the piston illustrated in FIG. 44;

[0066]FIG. 47 is a second side view of the piston illustrated in FIG.44;

[0067]FIG. 48 is a cross-sectional view of the piston illustrated inFIG. 46 taken along line 48-48 therein;

[0068]FIG. 49 is a cross-sectional view of a valve in accordance with atwelfth embodiment of the present invention, illustrated with a sealthereof in a first position;

[0069]FIG. 50 is a cross-sectional view of the valve illustrated in FIG.49 with the seal in a second position;

[0070]FIG. 51 is a cross-sectional view of a valve in accordance with athirteenth embodiment of the present invention, illustrated with a sealthereof in a first position; and

[0071]FIG. 52 is a cross-sectional view of the valve illustrated in FIG.51 with the seal in a second position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] FIGS. 1-17 illustrate a valve 20 in accordance with a firstembodiment of the present invention. FIG. 1 illustrates a particular useof the valve 20 to which the valve 20 is well suited. Of course, thevalve 20 may be used in a variety of other manners.

[0073] As illustrated in FIG. 1, the valve 20 may advantageously be usedto selectively control the flow of fluid to a catheter 22 from a fluidsource 24 such as an I.V. bag. In this arrangement, a first medicalimplement 21 is connected to the valve 20. The first medical implement21 comprises a tube 23 leading to a catheter 22. One end of the tube 23is connected to the valve 20, and the catheter 22 has its tip positionedin a patient.

[0074] A second medical implement 26 is also connected to the valve 20.The second medical implement 26 comprises a connecting member 27positioned at one end of a tube 29 which leads to the I.V. bag 24.

[0075] When so connected, the valve 20 permits fluid to flow from theI.V. bag 24 or other medical fluid source to the catheter 22 and intothe patient. The valve 20 is also arranged so that when the secondmedical implement 26 is disconnected, fluid flow through the valve 20 isprevented. In addition, when the second medical implement 26 isdisconnected, the valve 20 generates a “positive” fluid flow, i.e. flowof fluid in the direction of the patient, thereby preventing bloodclogging of the catheter 22.

[0076] The first embodiment of the valve 20 of the present inventionwill now be described in more detail. As illustrated in FIGS. 2-6, thevalve 20 includes a housing 28. The housing 28 is generally “T”-shaped,having a main portion with a first end 30 defining a first port 31 andhaving an opposing closed second end 32.

[0077] A branch 33 extends outwardly from the main portion of thehousing 28. The branch 33 has a third end 34 defining a second or branchport 35. (See FIG. 7.) Referring to FIG. 6, a main passage 36 is definedby an inner surface of a wall of the housing 28, and extends from thefirst end 30 to the second end 32 thereof. In addition, a branch passage38 extends from the main passage 36 through the branch port to the thirdend 34.

[0078] As stated above, the second end 32 of the housing 28 is closed.Preferably, an end cap 40 is positioned in the second end 32 of thehousing 28.

[0079] Excepting the branch portion 33, the housing 28 is generallycylindrical, as is the main passage 36. The first end 30 of the housing28 is adapted to receive the cannula tip or nose 37 of an ANSI standardsyringe, as illustrated in FIG. 12. As such, the passage 36 at the firstend has a diameter larger than the nose of this type of syringe. It is,however, contemplated that the diameter of the passage 36 can be of anysize to accommodate the attachment of other connector devices thereto.

[0080] Preferably, means are provided for locking the medical implement26 to the first end 30 of the valve 20. In the preferred embodiment,threads 44 are positioned on the outer surface of the housing 28 at thefirst end 30 for mating engagement with threads on the connector 27 ofthe second medical implement 26. Other locking means known to thoseskilled in the art may be used instead of the threads 44.

[0081] As the main passage 36 is generally cylindrical, the end cap 40is generally circular. The cap 40 engages the wall of the housing 28 atthe second end 32 to close the passage. The end cap 40 preferablyincludes an outwardly extending tab 46 on its peripheral edge forengaging the inside surface of the housing 28 in the passage 36 forlocking the end cap 40 in place.

[0082] For reasons described in more detail below, the diameter of thepassage 36 at the first end 30 of the housing 28 is smaller than that atthe second end 32. As illustrated, the passage 36 narrows (moving in adirection from the second towards the first end 32,30) near where thebranch passage 38 extends from the main passage 36. In addition, themain passage 36 narrows again beyond the branch passage 38 near thefirst end 30. A circumferential ledge 48 is formed at that point wherethe main passage 36 narrows near the first end 32.

[0083] As illustrated in FIGS. 11 and 12, a piston 42 is slidablypositioned within the main passage 36. Referring to FIGS. 13-17, thepiston 42 is generally cylindrical, having a maximum outer diameterwhich is just slightly smaller than the maximum diameter of the passage36. The piston 42 has a first end 50 and a second end 52 and a lengthfrom end to end which is less than the distance from the first end 30 tothe second end 32 of the housing 28.

[0084] The piston 42 has a head 54 at its first end 50. As illustrated,the head 54 is circular in outer shape, but has a slanted end surface56. A neck 58 extends from the head 54 to a body 60. The neck 58preferably has a reduced diameter as compared to the head 54. An“O”-ring 67 or similar seal is positioned around the reduced diameterneck 58 for engagement with the adjacent wall of the housing 28.

[0085] A first portion of the body 60 adjacent the neck 58 has a smallerdiameter than a second portion of the body 60 positioned nearer thesecond end 52. The transition between these two sections creates ashoulder 62. The shoulder 62 is arranged to engage the ledge 48 in thepassage 36 of the housing, preventing removal of the piston 42 from thefirst end 30 of the housing 28.

[0086] A pair of elongate cut-outs or depressions 64 are formed onopposite sides (i.e. 180 degrees from one another) in the second portionof the body 60 of the piston 42. The cut-outs 64 are trough shaped, andextend inwardly to a radial depth which is equal to the height of theshoulder 62 (so that the bottom of the cut-out is at the same level asthe exterior of the housing at the first portion of the body).

[0087] A groove 66 is formed in the piston 42 near its second end 52.Preferably, a seal 68 (see FIGS. 11 and 12) is positioned in this groove66. The seal 68 is preferably an “O”-ring comprised of rubber or asimilar resilient, sealing material.

[0088] In the preferred embodiment, the piston 42 is hollow, having arecessed area therein. As illustrated, the recessed area comprises abore or passage 72 extending inwardly from the second end 52 thereof Thebore 72 preferably has three diameters, the largest of which is near thesecond end 52, and tapering in diameter in two steps to two otherdiameters which are less than the first. The bore 72 is in communicationwith the passage 36 within the housing 28. The bore 72 preferably hasthe three diameters so that the wall of the housing 28 has a generallyuniform thickness, which facilitates molding. Those of skill in the artwill appreciate that the bore 72 may have more or less than threedifferent diameters.

[0089] The assembled valve 20, wherein the piston 42 is positioned inthe housing 28, is illustrated in FIGS. 7-12. As illustrated, the seal68 divides the main passage 36 into a first cavity or chamber 39 and asecond cavity or chamber 41. The first chamber 39 comprises the spacebetween the end cap 40 and the second end 52 of the piston 42, as wellas the space defined within the piston 42 by the bore 72. The secondchamber 41 is that space from the seal 68 to the first end 30 of thehousing 28 not occupied by the piston 42.

[0090] As illustrated in FIGS. 11 and 12, the piston 42 is moveable froma first or “uncompressed” position in which the shoulder 62 engages theledge 48 and the first end 50 of the piston 42 extends outwardly of thefirst end 30 of the housing 28, to a second or “compressed” position inwhich the piston 42 is moved in the direction of the second end 32 ofthe housing 28.

[0091] Means are provided for biasing the piston 42 into its firstposition. Preferably, this means comprises a spring 70. The spring 70 isof the helical variety, and has its first end engaging the cap 40 andits second end engaging the piston 42, preferably inside the bore 72 ata ledge created at a change in diameters thereof.

[0092] The first chamber 39 is air filled. In order to accommodate themovement of the piston 42 towards the second end 32 of the housing 28,an air vent 75 is preferably provided through the end cap 40 (see alsoFIG. 5). The air vent 75 is a passage through the cap 40 from thechamber 39 to the exterior of the valve 20 which allows air to flow intoand out of the chamber 39.

[0093] The branch 33 extends generally perpendicularly from theremainder of the housing 28 between its first and second ends 30,32. Thebranch 33 is generally defined by a cylindrical wall 76 extendingoutwardly from the wall which defines the main portion of the housing28. The wall 76 defines the branch passage 38.

[0094] As best illustrated in FIGS. 7 and 11-12, a threaded sleeve 78preferably extends about the branch of the housing 28. The sleeve 78 hasan inner diameter which is larger than the outer diameter of the wall76. In fact, the inner diameter is large enough to define a spacebetween the wall 76 and sleeve 78 in which the end of a tube or othermember may be inserted.

[0095] The sleeve 78 is preferably connected to the wall 76. Asillustrated in FIG. 7 and 9-12, the outer surface of the sleeve 78 has anumber of recesses 80 therein for aiding in gripping by a user.

[0096] The operation of the valve 20 will now be described in detailwith reference to the figures. A user first connects the first medicalimplement 21 to the branch port 35 at the third end 34. When the firstmedical implement 21 is of the type disclosed above, an end of the tube23 having a connector thereon is guided over the wall 76 between theoutside of the wall and the inside of the sleeve 78. The connector ispreferably threaded into engagement with the sleeve 78 to retain it inplace.

[0097] The user then engages the second medical implement 26 to thefirst port 31 of the valve 20. Preferably, the medical implement has ablunt cannula tip 37 positioned within a connector 27 having a matinglocking structure to the threads 44 or other locking means positioned onthe housing 28.

[0098] The user advances the cannula tip 37 until it engages the endsurface 56 of the piston 42. As the user further advances the implement,the piston 42 is pressed in the direction of the second end 32 of thehousing 28, compressing the spring 70. Air within the passage 36 betweenthe end cap 40 and the piston 42 and within the bore 72 of the piston isforced out through the vent 75 in the end cap 40.

[0099] Once the connector 27 of the implement 26 extends about the firstend 30 of the housing 28, the user locks the connector 27 to the housing28 to provide a secure connection. So engaged, the implement 26 isconnected to the valve 20 in the position illustrated in FIG. 12.

[0100] When the piston 42 is in this position, a fluid flow path isestablished from the second medical implement 26 (and through the tube29 from the I.V. bag 24 in the arrangement illustrated in FIG. 1)through the valve 20 to the first medical implement 21 (and thus throughthe catheter 22 to the patient). Fluid flows through the tip 37 of thecannula along the first end 54 of the piston 42 into the second chamber41, i.e. that space between the piston 42 and the inner surface of thehousing 28, including the space within the cut-outs 64. The total volumeof fluid within the valve 20 when the second medical implement isattached and fluid fills the second chamber 41 is an amount V1.

[0101] Fluid is prevented from travelling beyond the second end 52 ofthe piston 42 into the first chamber 39 by the seal 68. As a result, thefluid flowing from the second medical implement 26 towards the valve 20is forced to flow into the branch passage 38 and thereon into the tube23 to the patient.

[0102] Most importantly, when the second medical implement 26 isdisconnected from the valve 20, the valve 20 causes fluid to flow in thedirection of the first medical implement through the branch passage 38.As the second medical implement 26 is disconnected, the spring 70 forcesthe piston 42 towards the first end 30 of the housing 28. As the piston42 moves in this direction, the piston 42 slides through the narrowestportion of the passage 36 near the first end 30 of the housing 28. Thismovement causes the total volume or fluid space in the second chamber 41between the piston 42 and the housing 28 to reduce. Once the shoulder 62of the piston 42 hits the ledge 48, the piston stops moving, and thefluid volume within the valve 20 is at a minimum amount V2.

[0103] Because the fluid volume in the valve 20 decreases as the secondmedical implement 26 is disconnected, some fluid within the housing 28must be displaced. This fluid moves along the troughs 64 and into thebranch passage 38 in the direction of the patient, the total volume offluid flowing in the “positive” direction VD (volume displaced) beingequal to the difference between the maximum volume V1 less the minimumvolume V2.

[0104] Once the piston 42 has reseated, the valve 20 prevents later flowof fluid from the first medical implement 21 back through the valve 20,since the piston closes off the passage 36 near the first end 30 of thehousing 28. This prevents, for example, the blood pressure of thepatient from forcing blood back to the valve 20 and out the first port31.

[0105] Besides providing a positive flow, the valve 20 of the presentinvention has several other distinct advantages. First, it is often thecase that medical valves have a fluid containing area within them inwhich the fluid may stagnate. Fluid stagnation is undesirable, as it mayresult in bacteria growth and similar problems.

[0106] The valve 20 of the present invention has its fluid containingarea between the piston 42 and the wall of the housing 28 which definesthe main passage 36. This generally annular space is flushed each timefluid is injected from the top end 50 of the piston 42.

[0107] Another aspect of the present invention is that the end surface56 of the first end 50 of the piston 42 is smooth. This allows a user ofthe valve 20 to swab the cannula engaging surface before connecting themedical implement to the first port 31 of the valve. The swabbing may bewith alcohol or a similar disinfectant which serves to prevent the entryof bacteria and the like into the fluid system through the valve 20.

[0108] It may now be understood that the valve 20 includes both meansfor reducing the fluid volume or space therein when the second medicalimplement 26 is disconnected (i.e., in this case, a reduction in thevolume of chamber or cavity 41), and means for establishing a flow paththrough the valve 20 when the second medical implement 26 is connectedand for closing this fluid path when the implement is disconnected. Inthis first embodiment, these means are provided by the single piston 42.

[0109] A second embodiment valve 120 in accordance with the presentinvention is illustrated in FIGS. 18 and 19. As illustrated, this valve120 includes a housing 128 which is similar to the housing of the valve20 described above, except that this housing is shorter in lengthbetween a first end 128 and a second end 130, as a piston 142 of thevalve 120 is also shorter.

[0110] As illustrated, the first end 130 defines a first port 131, andthe opposing second end 132 is closed. A branch 133 extends to a thirdend 134 defining a branch port 135.

[0111] A main passage 136 extends from the first end 130 towards thesecond end 132 of the housing. The main passage 136 is defined by aninner surface of a wall of the housing 128. The main passage 136 isgenerally cylindrical in shape, in this embodiment having no ledges orsteps.

[0112] A branch passage 138 extends perpendicularly from the mainpassage 138 between the first and second ends 130,132 of the housing128. The branch passage 138 is preferably defined by a wall 176. Thebranch passage 138 is generally cylindrical in shape.

[0113] The piston 142 is movably positioned within the passage 136 ofthe housing 128. The piston 142 has a body 160 which is generallycylindrical in shape, and has a first end 150 and a second end 152. Thefirst end 150 defines a head 154 having a slanted surface. In thisembodiment, the piston 142 is similar to that of the first embodiment,except the piston is much shorter and does not have the differingdiameter sections.

[0114] A groove 166 is formed in the body 160 between its first andsecond ends 150,152. As illustrated, a seal 168 is positioned in thegroove 166 of the piston 142. This seal 168 divides the passage 136 inthe housing 128 into a first chamber 139 and a second chamber 141.

[0115] A recess or bore 172 is formed in the body 160 of the piston 142extending from the second end 152. A first end of a spring 170 ispositioned in the recess 172 and extends therefrom to the second end 132of the housing 128 for biasing the piston 142 towards the first end 130of the housing 128.

[0116] A vent 175 is provided through the second end 132 of the housing128. The vent 175 permits air to flow between the first chamber 139 andthe outside of the housing 128.

[0117] A resilient, pre-slit seal 182 is provided near the first end 130of the housing 128. The seal 182 is generally circular for fittingwithin the passage 136, and preferably includes a pre-formed slit 184through which the tip of a medical implement may pass. The seal 182 ispreferably constructed of a resilient material such that it naturallyreturns to the position (i.e. reseals) illustrated in FIG. 18, where theslit 184 is closed and fluid is prevented from passing therethrough.

[0118] As with the first embodiment, a sleeve 178 is positioned aboutthe wall 176 defining branch 133 of the housing 128. The sleeve 178preferably has threads 179 on an inner surface thereof.

[0119] The operation of the valve 120 will now be described in detailwith reference to FIGS. 18 and 19. A user first connects the firstmedical implement (not shown, but which may be similar to thatillustrated in FIG. 1) to the branch port 135 at the third end 134. Whenthe first medical implement is of the type disclosed above, the free endof the tube is guided over the wall 176 between the outside of the walland the inside of the sleeve 178.

[0120] The user then engages the second medical implement 126 to thefirst port 131 of the valve 120. Preferably, the medical implement has ablunt cannula tip 137.

[0121] The user advances the cannula tip 137 until it engages the endsurface 156 of the piston 142. As the user further advances theimplement, the piston 142 is pressed in the direction of the second end132 of the housing 128, compressing the spring 170. Air within the firstchamber 139 between the end cap 140 and the piston 142 and within thebore 172 of the piston is forced out through the vent 175 in the end cap140.

[0122] When the piston 142 is in this position (as illustrated in FIG.19), a fluid flow path is established from the second medical implement126 (such as through a tube from an I.V. bag) through the valve 120 tothe first medical implement (and thus through the catheter to thepatient). Fluid flows through the tip 137 of the cannula along the firstend 154 of the piston 142 into the second chamber 141. The total volumeof fluid within the valve 120 when the second medical implement isengaged and fluid fills the second chamber 141 is an amount V1.

[0123] Fluid is prevented from travelling beyond the seal 168 into thefirst chamber 139. As a result, the fluid flowing from the secondmedical implement 126 into the second chamber 141 is forced to flow intothe branch passage 138 and thereon into the tube to the patient.

[0124] Most importantly, when the second medical implement 126 isdisconnected from the valve 120, the valve 120 causes fluid to flow inthe direction of the first medical implement through the branch passage138. As the second medical implement 126 is disconnected, the spring 170forces the piston 142 towards the first end 130 of the housing 128. Thismovement causes the total volume or fluid space in the second chamber141 between the piston 142 and the seal 182 at the first end 130 of thehousing 128 to reduce. Once the piston 142 encounters the seal 182, thepiston stops moving, and the fluid volume within the valve 120 is at aminimum amount V2.

[0125] Because the fluid volume in the valve 120 decreases as the secondmedical implement 126 is disconnected, some fluid within the housing 128must be displaced. This fluid moves through the branch passage 138 inthe direction of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0126] Once the implement tip 137 is removed, the valve 120 preventslater flow of fluid from the first medical implement back through thevalve 120, since the slit 184 in the seal 182 reseals, closing off thepassage 136 near the first end 130 of the housing 128.

[0127] Besides providing a positive flow, the valve 120 of the presentinvention has other advantages. Again, the valve 120 of this embodimenthas its fluid containing area between the piston 142 and the housing 128which defines the main passage 136. This space is flushed each timefluid is injected from the top end 150 of the piston 142.

[0128] Advantageously, a needle may be used to penetrate the seal 182instead of the blunt tip cannula 137. In this arrangement, the seal 182is preferably resilient so that it reseals, but need not be pre-slit.

[0129] As may now be understood, the means for selectively establishingthe fluid flow path through the valve 120 and the means for causing areduction in fluid space in the valve 120 when the second medicalimplement 126 is removed are separate in this embodiment. In thisembodiment, the means for selectively establishing the fluid flow pathcomprises the seal 184, while the means for reducing the fluid spacecomprises the biased piston 142.

[0130] A third embodiment valve 220 in accordance with the presentinvention is illustrated in FIGS. 20 and 21. As illustrated, this valve220 includes a housing 228. As illustrated, the housing 228 is agenerally cylindrical body having a first end 230 defining a first port231 and having an opposing second end 232.

[0131] A main passage 236 extends from the first end 230 towards thesecond end 232 of the housing. The main passage 236 is defined by aninner surface of the housing 228. The main passage 236 is generallycylindrical in cross-section. An extension passage 238 of smallerdiameter extends from the main passage 238 to the second end 232 of thevalve 220, the passage 238 being defined partly by a wall 276. A sleeve278 is positioned about the outside of the wall 276. The sleeve 278preferably has threads 279 on an inner surface thereof.

[0132] The piston 242 is movably positioned within the passage 236 ofthe housing 228. The piston 242 has a body 260 having a generallycircular first end 250 or head. A flange or skirt 255 extends outwardlyfrom a circumference of the head 250. A number of passages 257 areprovided through the head 250 of the piston 242.

[0133] A biasing member 270 is positioned between the piston 242 and aledge 261 formed by the wall of the housing 238 at the intersection oftwo portions of the passage 236 having differing diameters. The biasingmember 270 is preferably an annular, compressible and generallyclose-cell material, such as foam or the like.

[0134] A resilient, pre-slit seal 282 is provided near the first end 230of the housing 228. The seal 282 is generally circular for fittingwithin the passage 236, and includes a preformed slit 284 through whichthe tip of a medical implement may pass. The seal 282 is preferablyconstructed of a resilient material such that when it returns to anunbiased position as illustrated in FIG. 20, the slit 284 is closed andfluid is prevented from passing therethrough.

[0135] The operation of the valve 220 will now be described in detailwith reference to FIGS. 20 and 21. A user first connects the firstmedical implement (not shown, but which may be similar to thatillustrated in FIG. 1) to the second end 232. When the first medicalimplement is of the type disclosed above, the free end of the tube isguided over the wall 276 between the outside of the wall and the insideof the sleeve 278. The user then engages the second medical implement226 with the first port 231 of the valve 220. Preferably, the medicalimplement has a blunt cannula tip 237.

[0136] The user advances the cannula tip 237 through the seal 282 untilit engages the end surface 256 of the piston 242. As the user furtheradvances the implement, the piston 242 is pressed in the direction ofthe second end 232 of the housing 228, compressing the biasing member270.

[0137] When the piston 242 is in this position (as illustrated in FIG.21), a fluid flow path is established from the second medical implement226 (such as through a tube from an I.V. bag) through the valve 220 tothe first medical implement (and thus through the catheter to thepatient). Fluid flows through the tip 237 of the cannula through thepassages 257 into the passage 236. In addition, fluid fills the space241 between the seal 282 and the piston 242. The total volume of fluidwithin the valve 220 when the second medical implement is engaged is anamount V1.

[0138] Most importantly, when the second medical implement 226 isdisconnected from the valve 220, the valve 220 causes fluid to flow inthe direction of the first medical implement through the extensionpassage 238. As the second medical implement 226 is disconnected, thebiasing member 270 forces the piston 242 towards the first end 230 ofthe housing 228. As the piston 242 moves in this direction, the biasingmember 270 expands. This causes the total volume or fluid space in thehousing 228 to reduce. Once the piston 242 encounters the seal 184, thepiston stops moving, and the fluid volume within the valve 220 is at aminimum amount V2.

[0139] Because the fluid volume in the valve 220 decreases as the secondmedical implement 226 is disconnected, some fluid within the housing 228must be displaced. This fluid moves through the branch passage 238 inthe direction of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0140] Once the implement tip 237 is removed, the valve 220 preventslater flow of fluid from the first medical implement back through thevalve 220, since the slit 284 in the seal 282 reseals, closing off thepassage 236 near the first end 230 of the housing 228.

[0141] Besides providing a positive flow, the valve 220 of the presentinvention has other advantages. The valve 220 of the present inventionhas its fluid containing area between the seal 282 and the housing 228which defines the main passage 236. This space is flushed each timefluid is injected from the top end 250 of the piston 242.

[0142] Another advantage is that the straight-through fluid flow pathfrom the first to the second end 230, 232 serves to eliminate stagnationareas.

[0143] A fourth embodiment valve 320 in accordance with the presentinvention is illustrated in FIGS. 22 and 23. This valve 320 includes ahousing 328 which is generally cylindrical in shape, like the housing228 of the third embodiment. The housing 328 has a first end 330defining a first port 331 and a second end 332 defining a second port335. A passage 336 extends through the housing 328 from end to end.

[0144] A piston 342 is movably positioned within the passage 336. Thepiston 342 has a generally circular head 354 with a flange or skirt 355extending downwardly therefrom circumferentially around the outer edgeof the head 354. At least one passage 357 is provided through the head354 of the piston 342.

[0145] A biasing element 370 is positioned within the housing 328between the piston 342 and the second end 332. As illustrated, theelement 370 is a resilient member which is circular in shape having agenerally “C” shaped cross-section with a closed interior side and anopen exterior side.

[0146] The element 370 cooperates with an inner surface of the housing328 to define a chamber 339 which is sealed from the passage 336. One ormore vents 375 are provided through the housing wall from a pointexterior thereof to the chamber 339.

[0147] In this embodiment, a sleeve 378 is surrounding a wall 376 isformed integrally with the remainder of the housing 328. The sleeve 378has threads 379 on an inner surface thereof for use in mating engagementwith threads on a medical connector.

[0148] A seal 382 is provided near the first end 330 of the housing 328.The seal 382 preferably selectively obscures or seals the passage 336through the housing 328. The seal 382 is pre-cut to form a slit 384which, when the seal 382 is in its unbiased position as illustrated inFIG. 22, is closed.

[0149] Use of the valve 320 of this embodiment is as follows. A userfirst connects a first medical implement (see FIG. 1) to the port 335 atthe second end 334 of the housing 328. When the first medical implementis of the type disclosed above, a free end of the tube is guided overthe wall 376 between the outside of the wall and the inside of thesleeve 378.

[0150] The user then engages the second medical implement 326 with thefirst port 331 of the valve 320. Preferably, the medical implement has ablunt cannula tip 337. The user advances the cannula tip 337 through theslit 384 in the seal 382 until it engages the end surface 354 of thepiston 342. As the user further advances the implement, the piston 342is pressed in the direction of the second end 332 of the housing 328,compressing the biasing element 370 radially outward. Air within thechamber 339 is forced out through the vents 375 in the wall of thehousing 328.

[0151] When the piston 342 is in this position, a fluid flow path isestablished from the second medical implement through the valve 320 tothe first medical implement. Fluid flows through the tip 337 of thecannula through the passage 357 in the first end 354 of the piston 342into the passage 336. The total volume of fluid within the valve 320when the second medical implement is attached and fluid fills thepassage 336 with the biasing element 370 compressed is an amount V1.

[0152] Most importantly, when the second medical implement 326 isdisconnected from the valve 320, the valve 320 causes fluid to flow inthe direction of the first medical implement through the second port335. As the second medical implement 326 is disconnected, the biasingelement 370 forces the piston 342 towards the first end 330 of thehousing 328.

[0153] At the same time, the biasing element 370 expands inwardly,causing a reduction in the total volume or fluid space in the passage336 between the piston 342 and second end 332 of the housing 328 toreduce. Once the piston 342 moves upwardly to a point at which itencounters the seal 382, the piston stops moving, and the fluid volumewithin the valve 320 is at a minimum amount V2.

[0154] Because the fluid volume in the valve 320 decreases as the secondmedical implement 326 is disconnected, some fluid within the housing 328must be displaced. This fluid moves through the passage 336 in thedirection of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0155] Once the implement tip 337 is removed, the valve 320 preventslater flow of fluid from the first medical implement therethrough, sincethe seal 382 closes off the passage 336 near the first end 330 of thehousing 328.

[0156] Besides providing a positive flow, the valve 320 of the presentinvention has other advantages. Fluid stagnation is generally preventedsince the fluid flows through the housing 328 in generally a straightpath.

[0157] A fifth embodiment valve 420 in accordance with the presentinvention is illustrated in FIGS. 24 and 25. This valve 420 includes ahousing 428 which is generally identical to the housing 328 of the valve320 described above and illustrated in FIGS. 22 and 23, having a firstend 430 defining a first port 431 and a second end 432 defining a secondport 435. A passage 436 extends through the housing 428 from the firstto the second ends 430, 432.

[0158] Again, a portion of the passage 436 near the second end 432 isdefined by a wall 476. A sleeve 478 extends about the wall 476, thesleeve 478 having a number of threads 479 on an internal surfacethereof.

[0159] A seal 482 which has a pre-cut slit 484 is provided near thefirst end 430 of the housing 428 as in the last embodiment.

[0160] In this embodiment, the biasing element 470 comprises adonut-shaped, resilient element having a hollow interior 471. Theinterior 471 of the element 470 is in communication with the outside ofthe housing 428 via one or more passages or vents 475. A connection isprovided between the element 470 and the passages 475, however, so thatair flowing through the passages 475 to or from the element 470 does notflow into the passage 436.

[0161] In this embodiment, a pair of pistons 442,443 move radiallyinstead of linearly as in the previously described embodiments. Eachpiston 442,443 preferably includes a head 450 and a base 452 which arehalf-circle shaped. An upstanding wall 455 connects the head and base450, 452 of each piston 442, 443 in a manner that the head and basethereof extends radially outwardly around a portion of the biasingelement 470. Each piston 442, 443 preferably has a tapered area 453 inthe head 450 thereof, the area 453 in the pistons 442, 443 cooperatingto form a guide, as described in more detail below.

[0162] The pistons 442, 443 are arranged to abut each other along theirwalls 455 in their normal position, as illustrated in FIG. 24. Thepistons 442, 443 are arranged to move radially outward when a medicalimplement is pressed between them, as illustrated in FIG. 25.

[0163] Use of the valve 420 of this embodiment is as follows. A userfirst connects a first medical implement (see FIG. 1) to the port 435 atthe second end 434 of the housing 428. When the first medical implementis of the type disclosed above, a free end of the tube is guided overthe wall 476 between the outside of the wall and the inside of thesleeve 478.

[0164] The user then engages the second medical implement 426 to thefirst port 431 of the valve 420. Preferably, the medical implement has ablunt cannula tip 437. The user advances the cannula tip 437 through theslit 484 in the seal 482 until it engages the head 450 of each piston442,443. As the user further advances the implement, the pistons 442,443are pressed radially outwardly from one another, compressing the biasingelement 470. Air within the hollow interior 471 of the biasing element470 is forced out through the vents 375 in the wall of the housing 328.

[0165] When in this position, a fluid flow path is established from thesecond medical implement 426 through the valve 420 to the first medicalimplement. Fluid flows through the tip 437 of the cannula into thepassage 436. The total volume of fluid within the valve 420 when thesecond medical implement is attached and fluid fills the passage 436with the biasing element 470 compressed is an amount V1.

[0166] Most importantly, when the second medical implement 426 isdisconnected from the valve 420, the valve 420 causes fluid to flow inthe direction of the first medical implement through the second port435. As the second medical implement 426 is disconnected, the biasingelement 470 forces the pistons 442,443 radially inwardly to thatposition illustrated in FIG. 24.

[0167] At the same time, the biasing element 470 expands inwardly,causing a reduction in the total volume or fluid space in the passage436 between the piston 442 and second end 432 of the housing 428. Oncethe pistons 442,443 encounter one another, they stop moving and thevolume within the valve 420 is at a minimum amount V2.

[0168] Because the fluid volume in the valve 420 decreases as the secondmedical implement 426 is disconnected, some fluid within the housing 428must be displaced. This fluid moves through the passage 436 in thedirection of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0169] Once the tip 437 of the implement 426 is removed, the valve 420prevents later flow of fluid from the first medical implementtherethrough, since the seal 482 closes off the passage 436 near thefirst end 430 of the housing 428.

[0170] Besides providing a positive flow, the valve 420 of the presentinvention has other advantages. Fluid stagnation is generally preventedsince the fluid flows through the housing 428 in generally a straightpath.

[0171] As will be appreciated by those skilled in the art, there may beprovided more than two pistons cooperating together to perform theabove-described function, such as three or four “pie”-shaped pistons.

[0172] A sixth embodiment valve 520 in accordance with the presentinvention is illustrated in FIGS. 26 and 27. This embodiment valve 520is similar to the first embodiment valve 20, except that the valve 520is arranged to have a direct flow-through arrangement similar to thatillustrated in the last embodiment.

[0173] The valve 520 of this embodiment has a housing 528 which isgenerally cylindrical in shape. The housing 528 has a first end 530defining a first port 531 and a second end 532 defining a second port535. A passage 536 extends through the housing 528 from end to end.

[0174] A piston 542 is movably positioned within the passage 336. Thepiston 542 has a generally circular head 554 with a tubular section 555extending centrally downwardly therefrom. A passage 557 is providedthrough the head 554 and tubular section 555 of the piston 542.

[0175] A spring 570 or other means for biasing is positioned within thehousing 528 between the head 554 of the piston 542 and a ledge 561formed in the housing 528 along the passage 536 between the first andsecond ends 530, 532.

[0176] A seal 568 is provided in a groove in the circumferential surfaceof the head 554 of the piston 542. A similar seal 568 is provided aroundthe tubular section 555 near its end opposite the head 554. The seals568, 569 seal off a portion of the passage 536, thereby defining asealed, air-filled chamber 539.

[0177] One or more vents 575 are provided through the housing wall froma point exterior thereof to the chamber 539.

[0178] The sleeve 578 and wall portion 576 are integrally formed withthe remainder of the housing, the wall 576 defining the passage 536 atthe second end 532. The sleeve 578 has threads 579 thereon for use inmating engagement with threads on a medical connector.

[0179] A seal 582 is provided near the first end 530 of the housing 528.The seal 582 preferably obscures or seals the passage 536 through thehousing 528. The seal 582 is pre cut to form a slit 584 which, when theseal 582 is in its unbiased position as illustrated in FIG. 26, isclosed.

[0180] Use of the valve 520 of this embodiment is as follows. A userfirst connects a first medical implement (see FIG. 1) to the port 535 atthe second end 534 of the housing 528. When the first medical implementis of the type disclosed above, a free end of the tube is guided overthe wall 576 between the outside of the wall and the inside of thesleeve 578.

[0181] The user then engages the second medical implement 526 to thefirst port 531 of the valve 520. Preferably, the medical implement has ablunt cannula tip 537. The user advances the cannula tip 537 through theslit 584 in the seal 582 until it engages the head 554 of the piston542. As the user further advances the implement, the piston 542 ispressed in the direction of the second end 532 of the housing 528,compressing the spring 570. Air within the chamber 539 is forced outthrough the vents 575 in the wall of the housing 528.

[0182] When the piston 542 is in this position (as illustrated in FIG.27), a fluid flow path is established from the second medical implementthrough the valve 520 to the first medical implement. Fluid flowsthrough the tip 537 of the cannula through the passage 557 in the piston542 into the passage 536. Fluid also fills the space between the seal582 and the head 554 of the piston 542. The total volume of fluid withinthe valve 520 when the second medical implement is attached and fluidfills these areas when the spring 570 is compressed is an amount V1.

[0183] Most importantly, when the second medical implement 526 isdisconnected from the valve 520, the valve 520 causes fluid to flow inthe direction of the first medical implement through the second port535. As the second medical implement 526 is disconnected, the spring 570forces the piston 542 towards the first end 530 of the housing 528. Thispiston 542 movement causes a reduction in the total volume or fluidspace in the passage 536 between the piston 542 and second end 532 ofthe housing 528. Once the piston 542 moves upwardly to a point at whichit encounters the seal 582, the piston stops moving, and the fluidvolume within the valve 520 is at a minimum amount V2.

[0184] Because the fluid volume in the valve 520 decreases as the secondmedical implement 526 is disconnected, some fluid within the housing 528must be displaced. This fluid moves through the passage 536 in thedirection of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0185] Once the implement tip 537 is removed the valve 520 preventslater flow of fluid from the first medical implement therethrough, sincethe seal 582 closes off the passage 536 near the first end 530 of thehousing 528.

[0186] Besides providing a positive flow, the valve 520 of the presentinvention has other advantages. Fluid stagnation is generally preventedsince the fluid flows through the housing 528 in a continuous path.

[0187] A seventh embodiment valve 620 in accordance with the presentinvention is illustrated in FIGS. 28 and 29. This valve 620 includes ahousing 628 which is similar to those described above with respect tovalves 320, 420 and 520.

[0188] The housing 628 has a first end 630 defining a first port 631 anda second end 632 defining a second port 635. A passage 636 extendsthrough the housing 628 from the first to the second ends 630, 632.

[0189] Again, a portion of the passage 636 near the second end 632 isdefined by a wall 676. A sleeve 678 extends about the wall 676, thesleeve 678 having a number of threads 679 on an internal surfacethereof.

[0190] A seal 682 which has a pre-cut slit 684 is provided near thefirst end 630 of the housing 628 as in the last embodiment.

[0191] A piston 642 is positioned adjacent the seal 684. The piston 642is preferably generally disc-shaped, having a circular outer shape. Thepiston 642 has a top or first end 650 which is slanted, and a second orbottom end 652 which is flat.

[0192] In this embodiment, a resilient element 670 comprises a generallycylindrical, resilient and non-porous material. In its resting state,the element 670 preferably has an outer diameter which is smaller thanthe diameter of the passage 636 in which it is positioned. The element670 is positioned on a ledge 661 formed within the passage 636, and thebottom end 652 of the piston 642.

[0193] Grooves 685, 686 are formed in the side wall of the housing 628within the passage 636, including the portion defining the ledge 661.The grooves 685, 686 are arranged to support the outside surfaces of theelement 670 in a manner which permits fluid to flow between the element670 and the housing 628, as described below.

[0194] Use of the valve 620 of this embodiment is as follows. A userfirst connects a first medical implement (see FIG. 1) to the port 635 atthe second end 634 of the housing 628. When the first medical implementis of the type disclosed above, a free end of the tube is guided overthe wall 676 between the outside of the wall and the inside of thesleeve 678.

[0195] The user then engages the second medical implement 626 to thefirst port 631 of the valve 620. Preferably, the medical implement has ablunt cannula tip 637. The user advances the cannula tip 637 through theslit 684 in the seal 682 until it engages the top 650 of the piston 642.As the user further advances the implement, the piston 642 is presseddownwardly compressing the element 670.

[0196] When in this position, a fluid flow path is established from thesecond medical implement 626 through the valve 620 to the first medicalimplement. Fluid flows through the tip 637 of the cannula through thepassage 636. Fluid is allowed to flow past the element 670 through thegrooves 685, 686. The total volume of fluid within the valve 620 whenthe second medical implement is attached and fluid fills the passage 636and that space between the top 650 of the piston 642 and the bottom ofthe seal 682 when the piston 642 is depressed is an amount V1.

[0197] Most importantly, when the second medical implement 626 isdisconnected from the valve 620, the valve 620 causes fluid to flow inthe direction of the first medical implement through the second port635. As the second medical implement 626 is disconnected, the element670 expands, forcing the piston 642 upwardly to that positionillustrated in FIG. 28.

[0198] At the same time, a reduction in the total volume or fluid spacein the passage 636 between the piston 642 and seal 682 occurs. Once thepiston 642 moves upwardly to a point at which it encounters the seal682, the piston stops moving, and the fluid volume within the valve 620is at a minimum amount V2.

[0199] Because the fluid volume in the valve 620 decreases as the secondmedical implement 626 is disconnected, some fluid within the housing 628must be displaced. This fluid moves through the passage 636 in thedirection of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0200] Once the tip 637 of the implement 626 is removed, the valve 620prevents later flow of fluid from the first medical implementtherethrough, since the seal 682 closes off the passage 636 near thefirst end 630 of the housing 628.

[0201] Besides providing a positive flow, the valve 620 of the presentinvention has other advantages. Fluid stagnation is generally preventedsince the fluid flows through the housing 628 in generally a straightpath.

[0202] An eighth embodiment valve 720 in accordance with the presentinvention is illustrated in FIGS. 30 and 31. This valve 720 includes ahousing 728 which is similar to those described above with respect tovalves 220, 320 etc.

[0203] The housing 728 has a first end 730 defining a first port 731 anda second end 732 defining a second port 735. A passage 736 extendsthrough the housing 728 from the first to the second ends 730, 732.

[0204] Again, a portion of the passage 736 near the second end 732 isdefined by a wall 776. A sleeve 778 extends about the wall 776, thesleeve 778 having a number of threads 779 on an internal surfacethereof.

[0205] A seal 782 which has a pre-cut slit 784 is provided near thefirst end 730 of the housing 728 as in the last embodiment.

[0206] In this embodiment, a resilient element 770 comprises a generallycylindrical, resilient and hollow member. In its resting state, theelement 770 preferably has an outer diameter which is smaller than thediameter of the passage 736 in which it is positioned. The element 770defines a interior space 771 which is sealed from the passage 736. Theelement 770 is positioned on a ledge 761 formed within the housing 728.A sloped cannula-engaging surface 781 is defined at the top of theelement 770.

[0207] A vent 775 extends through the housing 628 from the interiorspace 771 within the element 770 to a point exterior of the housing 628.In the embodiment illustrated, the vent 775 terminates in the spacebetween the wall 776 and the sleeve 778.

[0208] Use of the valve 720 of this embodiment is as follows. A userfirst connects a first medical implement (see FIG. 1) to the port 735 atthe second end 734 of the housing 728. When the first medical implementis of the type disclosed above, a free end of the tube is guided overthe wall 776 between the outside of the wall and the inside of thesleeve 778.

[0209] The user then engages the second medical implement 726 to thefirst port 731 of the valve 720. Preferably, the medical implement has ablunt cannula tip 737. The user advances the cannula tip 737 through theslit 784 in the seal 782 until it engages the sloped surface 781 at thetop of the element 770. As the user further advances the implement, theelement 770 is compressed downwardly and outwardly, reducing the volumeof the space 771, but increasing the fluid space within the valve 720.

[0210] When in this position, a fluid flow path is established from thesecond medical implement 726 through the valve 720 to the first medicalimplement. Fluid flows through the tip 737 of the cannula along thesloped surface 781 (whereby the tip of the cannula is not obstructed)and through the passage 736. The total volume of fluid within the valve720 when the second medical implement is attached and fluid fills thepassage 736 and that space between the top of the element 770 and thebottom of the seal 782 is an amount V1.

[0211] Most importantly, when the second medical implement 726 isdisconnected from the valve 720, the valve 720 causes fluid to flow inthe direction of the first medical implement through the second port735. As the second medical implement 726 is disconnected, the element770 moves upwardly to that position illustrated in FIG. 30.

[0212] At the same time, a reduction in the total volume or fluid spacein the passage 736 between element 770 and the seal 782 occurs, untilthe fluid volume within the valve 720 is at a minimum amount V2.

[0213] Because the fluid volume in the valve 720 decreases as the secondmedical implement 726 is disconnected, some fluid within the housing 728must be displaced. This fluid moves through the passage 736 in thedirection of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0214] Once the tip 737 of the implement 726 is removed, the valve 720prevents later flow of fluid from the first medical implementtherethrough, since the seal 782 closes off the passage 736 near thefirst end 730 of the housing 728.

[0215] Besides providing a positive flow, the valve 720 of the presentinvention has other advantages. Fluid stagnation is generally preventedsince the fluid flows through the housing 728 in generally a straightpath.

[0216] A ninth embodiment valve 820 in accordance with the presentinvention is illustrated in FIGS. 32 and 33. As illustrated, this valve820 includes a housing 828 which is somewhat similar to the housings ofthe valves 220, 320 etc. described above.

[0217] As illustrated, the housing 828 has a body having a first end 830defining a first port 831 and an opposing second end 832. A main passage836 extends from the first end 830 towards the second end 832 of thehousing. The main passage 836 is defined by an inner surface of a wallof the housing 828. The main passage 836 is cylindrical in shape.

[0218] An extension passage 838 extends from the main passage 836 to thesecond end 832. The extension passage 838 is preferably defined by awall 876 and is generally cylindrical in shape, although smaller indiameter than the main passage 836.

[0219] A resilient, seal 882 is provided near the first end 830 of thehousing 828. The seal 882 has a generally circular or peripheral outershape for fitting within the passage 836, and preferably includes apre-formed slit 884 through which the tip of a medical implement maypass. The seal 882 is preferably constructed of a resilient materialsuch that it naturally returns to the position as illustrated in FIG.32, where the slit 884 is closed and fluid is prevented from passingtherethrough.

[0220] More importantly, however, the seal 882 is arranged so that whenan implement is pressed through the slit 884, at least a portion of theseal 882 moves in the direction of the first end 830 of the housing 828whereby the fluid space or volume inside the housing 828 increases. Atthe same time, the seal 882 is arranged so that when the implement isretracted, the seal 882 moves in the direction of the second end 832 ofthe housing 828, reducing the fluid space or volume therein.

[0221] A sleeve 878 is positioned about the wall 876 at the second end832 of the housing 828. The sleeve 878 preferably has threads 879 on aninner surface thereof.

[0222] The operation of the valve 820 will now be described in detailwith reference to FIGS. 32 and 33. A user first connects the firstmedical implement (not shown, but which may be similar to thatillustrated in FIG. 1) to the branch port 835 at the third end 834. Whenthe first medical implement is of the type disclosed above, the free endof the tube is guided over the wall 876 between the outside of the walland the inside of the sleeve 878.

[0223] The user then engages the second medical implement 826 to thefirst port 831 of the valve 820. Preferably, the medical implement has ablunt cannula tip 837. The user advances the cannula tip 837 through theslit 884 in the seal 882. At this time, the seal 882 moves into theposition as illustrated in FIG. 33.

[0224] When in this position, a fluid flow path is established from thesecond medical implement 826 (such as through a tube from an I.V. bag)through the valve 820 to the first medical implement (and thus throughthe catheter to the patient). Fluid flows through the tip 837 of thecannula through the main passage 836 and extension passage 838. Thetotal volume of fluid within the valve 820 when the second medicalimplement is attached is an amount V1.

[0225] Most importantly, when the second medical implement 826 isdisconnected from the valve 820, the valve 820 causes fluid to flow inthe direction of the first medical implement through the extensionpassage 838. As the second medical implement 826 is disconnected, theseal 882 moves back to its position as illustrated in FIG. 32. Thiscauses the total volume or fluid space in the housing 828 to reduce to aminimum amount V2.

[0226] Because the fluid volume in the valve 820 decreases as the secondmedical implement 826 is disconnected, some fluid within the housing 828must be displaced. This fluid moves through the branch passage 838 inthe direction of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0227] Once the implement tip 837 is removed, the valve 820 preventslater flow of fluid from the first medical implement therethrough, sincethe slit 884 in the seal 882 reseals, closing off the passage 836 nearthe first end 830 of the housing 828.

[0228] Besides providing a positive flow, the valve 820 of the presentinvention has other advantages. The valve 820 of the present inventionhas its fluid containing area between the seal 882 and the housing 828which defines the main passage 836. This space is flushed each timefluid is injected through the implement 826.

[0229] A tenth embodiment valve 920 in accordance with the presentinvention is illustrated in FIGS. 34 and 35. As illustrated, the housing928 has a body having a first end 930 defining a first port 931 and anopposing closed second end 932. A branch 933 extends to a third end 934defining a branch port 935.

[0230] An opening in the housing 928 at its first end leads to a chamber936 or passage on one side of a diaphragm member 970 to a branch passage938. The branch passage 938 extends from the chamber 936 in thedirection opposite the second end 930 of the housing 928. The branchpassage 938 is preferably defined by a wall 976. The branch passage 938is generally cylindrical in shape.

[0231] A resilient, pre-slit seal 982 is provided near the first end 930of the housing 928. The seal 982 is generally circular for fittingwithin the opening in the first end 930 of the housing 928. The seal 982preferably includes a pre-formed slit 984 through which the tip of amedical implement may pass. The seal 982 is preferably constructed of aresilient material such that it naturally returns to the positionillustrated in FIG. 34, where the slit 984 is closed and fluid isprevented from passing therethrough.

[0232] The diaphragm 970 is positioned within a hollow space within thehousing 928 between the first and second ends 920,932. The diaphragm 970generally divides this space into the first chamber or cavity 936 and asecond chamber 939. The diaphragm 970 is biased in an upward direction,i.e., in the direction of the first end 930 of the housing 929.

[0233] At least one vent 975 extends through the wall of the housing 928at its second end 932 to the second chamber 939, permitting air to flowin and out of the chamber.

[0234] As with the first embodiment, a sleeve 978 is positioned aboutthe branch 933 of the housing 928. The sleeve 978 preferably has threads979 on an inner surface thereof.

[0235] The operation of the valve 920 will now be described in detailwith reference to FIGS. 34 and 35. A user first connects the firstmedical implement (not shown, but which may be similar to thatillustrated in FIG. 1) to the branch port 935 at the third end 934. Whenthe first medical implement is of the type disclosed above, the free endof the tube is guided over the wall 976 between the outside of the walland the inside of the sleeve 978.

[0236] The user then engages the second medical implement 926 to thefirst port 931 of the valve 920. Preferably, the medical implement has ablunt cannula tip 937. The user advances the cannula tip 937 through theslit 984 in the seal 982 and presses upon the diaphragm 970. At thistime, the diaphragm 970 moves into the position as illustrated in FIG.35.

[0237] When in this position (as illustrated in FIG. 35), a fluid flowpath is established from the second medical implement 926 (such asthrough a tube from an I.V. bag) through the valve 920 to the firstmedical implement (and thus through the catheter to the patient). Fluidflows through the tip 937 of the cannula into the chamber 936, thenthrough the branch passage 938. The total volume of fluid within thevalve 920 when the second medical implement is attached is an amount V1.

[0238] Most importantly, when the second medical implement 926 isdisconnected from the valve 920, the valve 920 causes fluid to flow inthe direction of the first medical implement through the branch passage938. As the second medical implement 926 is disconnected, the diaphragm970 moves upwardly back to its position as illustrated in FIG. 34. Thiscauses the total volume or fluid space in the housing 928 to reduce to aminimum amount V2.

[0239] Because the fluid volume in the valve 920 decreases as the secondmedical implement 926 is disconnected, some fluid within the housing 928must be displaced. This fluid moves through the branch passage 938 inthe direction of the patient, the total volume of fluid flowing in the“positive” direction being equal to the difference between the maximumvolume V1 less the minimum volume V2.

[0240] Further, once the implement tip 937 is removed, the valve 920prevents later flow of fluid from the first medical implementtherethrough, since the slit 984 in the seal 982 reseals, closing offthe passage 936 near the first end 930 of the housing 928.

[0241] Besides providing a positive flow, the valve 920 of the presentinvention has other advantages. The valve 920 of the present inventionhas its fluid containing area between the seal 982 and the housing 928which defines the chamber 936. This space is flushed each time fluid isinjected through the implement 926.

[0242] An eleventh embodiment valve 1020 in accordance with the presentinvention is illustrated in FIGS. 36-49. This valve 1020 is similar inmany respects to the valve of the first embodiment.

[0243] Referring to FIG. 36, the valve 1020 includes a housing 1028which is “T”-shaped, having a main portion with a first end 1030 and anopposing, closed second end 1032. A branch 1033 extends outwardly fromthe main portion generally perpendicular thereto to a third end 1034defining a branch port 1035.

[0244] As illustrated in FIGS. 38 and 39, a main passage 1036 extendsfrom the first end 1030 to the closed second end 1032 inside of thehousing 1028. In addition, a branch passage 1038 extends from the mainpassage 1036 through the branch port to the third end 1034.

[0245] The main passage 1036 has two diameters. A first small diameterportion of the passage 1036 extends from the first end 1030 to near thebranch passage 1038. The diameter of the main passage 1036 thenincreases to a larger diameter section extending to the second end 1032.A ledge 1048 is formed at the intersection of these two portions of themain passage 1036.

[0246] A piston 1042 is slidably positioned within the main passage1036. Referring to FIGS. 44-48, the piston 1042 is generallycylindrical, having a maximum outer diameter which is slightly less thanthe maximum diameter of the passage 1036. The piston 1042 has a firstend 1050 and a second end 1052 and a length from end to end which isless than the distance from the first end 1030 to the second end 1032 ofthe housing 1028.

[0247] The piston 1042 has a first body portion 1054 extending from thefirst end 1050 to a second body portion 1056. The outer diameter of thesecond body portion 1056 is larger than that of the first body portion1054, with a shoulder 1062 defining the intersection of these twoportions. This shoulder 1062 is arranged to engage the ledge 1048 in thehousing 1028 in a manner described below.

[0248] A groove 1066 is formed in the piston 1042 near its second end1052. Preferably, a seal 1068 (see FIGS. 38 and 39) is positioned inthis groove 1066. The seal 1068 preferably comprises an “O”-ring.

[0249] A “V”-shaped notch or cutout 1064 is defined in the first bodyportion 1056 of the piston 1042. This notch 1064 extends from the firstend 1050 towards the second end 1052.

[0250] In the preferred embodiment, the piston 1042 is hollow, having arecessed area therein. As illustrated, this area comprises a bore 1072extending into the piston 1042 from the second end 1052. As illustrated,the bore 1072 has two portions of differing diameters, thereby forming aledge. When the piston 1042 is positioned in the housing 1028 (see FIGS.38 and 39) the bore 1072 is in communication with the passage 1036.

[0251] A seal 1082 is provided at the first end 1030 of the housing 1028and closes the main passage 1036 at that end. The seal 1082 ispreferably mounted to the housing 1028 by an end cap 1083.

[0252] The seal 1082 is preferably a resilient, pre-slit re-sealableelement. The end cap 1083 has an end with a passage 1085 therethroughwhich is aligned with the main passage 1036. A cylindrical side wall1087 extends from the end of the cap 1083 and is arranged to engage theoutside of the housing 1028 at the first end 1030. As illustrated, thecap 1083 has a groove on the inside of the wall 1087 which accepts a rib1089 on the exterior of the housing 1028 in a snap-fit arrangement.

[0253] As with the previous embodiments, the branch passage 1038 isdefined by a wall structure 1076 which extends outwardly from the mainportion of the housing 1028. A sleeve 1078 is spaced outwardly from thiswall structure 1076. Threads 1079 are positioned on the inside of thesleeve 1078.

[0254] The assembled valve 1020, wherein the piston 1042 is positionedin the main passage 1036 through the housing 1028, is best illustratedin FIGS. 38 and 39. As illustrated, the seal 1068 divides the mainpassage 1036 into a first chamber 1039 and a second chamber 1041. Thefirst chamber 1039 comprises a space between the closed second end 1032of the housing 1028, the second end 1052 of the piston 1042, and thatspace within the bore 1072 in the piston 1042. The second chamber 1041is that space between the seal 1068 on the piston 1042 and the seal 1082at the first end 1030 of the housing 1028.

[0255] As illustrated, the piston 1042 is moveable from a first or“uncompressed” position in which the shoulder 1062 engages the ledge1048, to a second or “compressed” position in which the piston 1042 ismoved towards the second end 1032 of the housing 1028.

[0256] Means are provided for biasing the piston 1042 into its firstposition. Preferably, this means comprises a spring 1070. Asillustrated, the spring 1070 is a helical spring extending between thesecond end 1032 of the housing 1028 and the ledge formed in the piston1042 by the changing diameter bore 1072.

[0257] The first chamber 1039 is air-filled. In order to accommodate themovement of the piston 1042 towards the second end 1032 of the housing1028, an air vent 1075 is provided through the second end 1032.

[0258] The operation of the valve 1020 will now be described. A userfirst connects a first medical implement to the branch port 1035 in amanner as described above. The user then presses a blunt tip cannula orother medical implement 1037 (see FIG. 39) through the opening 1085 inthe cap 1083, and then through the slit in the seal 1082. The useradvances the implement 1037 until it presses the piston 1042 towards thesecond end 1032 of the housing 1028, as illustrated in FIG. 39.

[0259] When the piston 1042 is in this position, a flow path isestablished from the implement 1037 through the second chamber 1041between the outside of the piston 1042 and the wall of the housing 1028to the branch passage 1038. Fluid freely flows through the tip of thecannula 1037 because the open “V”-shaped spaced is provided below thetip at the first end 1050 of the piston 1052. In this position, thevalve 1020 has a maximum fluid capacity V1.

[0260] When the user removes the cannula 1037, the pre-slit seal in theseal 1082 reseals, preventing fluid from flowing from the main passage1026 out the first end 1030 of the valve 1020. At the same time, whenthe cannula 1037 or other implement is withdrawn, the piston 1042 movesupwardly to the position illustrated in FIG. 38 as a result of thespring force. When the piston 1042 is in the position illustrated inFIG. 38, the volume within the valve 1020 is at a minimum V2.

[0261] Because the fluid volume in the valve 1020 decreases as thepiston 1042 moves upwardly, some fluid in the main passage 1026 isdisplaced. This fluid volume V1-V2 moves along the piston 1042 to thebranch passage 1038.

[0262] This valve 1020 also has the advantage that flushing occurs ateach use and the seal 1082 may be swabbed at its top surface tosterilize it.

[0263] A twelfth embodiment valve 1120 in accordance with the presentinvention is illustrated in FIGS. 49 and 50. The valve 1120 of thisembodiment has a housing 1128 defining a main passage 1136 extendingfrom a first end 1130 to a chamber 1141. A branch passage 1138 leadsfrom the chamber 1141 generally perpendicular to the main passage 1136.

[0264] The housing 1128 has a second end 1132 opposite the first end1130, the second end 1132 being open to the chamber 1141.

[0265] A seal 1182 is positioned within the chamber 1141. Asillustrated, the seal 1182 is a resilient inverted “U”-shaped member. Ina first position, the seal 1182 is arranged to close the branch passage1138 from the chamber 1141 (see FIG. 49).

[0266] A piston 1142 is positioned within the main passage 1136 andrests upon a top portion of the seal 1182. As illustrated, the piston1142 has a flat first end 1150 and a slanted second end 1152. The piston1142 is generally cylindrical in cross-sectional shape.

[0267] The wall defining the main passage 1136 is cylindrical at thefirst end 1130 of the housing 1128. In a direction towards the secondend 1132, the wall slants outward to define a sloped surface 1148.

[0268] A seal 1168 is preferably provided at the first end 1130 of thehousing 1128. This seal 1168 is designed to seal against the outside ofthe piston 1142 to prevent fluid flow between the piston 1142 andhousing 1128 at the first end 1130 of the valve 1120.

[0269] The operation of this valve 1120 is as follows. A user moves thetip of a cannula or other medical implement into engagement with thefirst end 1150 of the piston 1142. The user presses the piston 1142towards the second end 1132 of the housing 1128 until the luer-lockconnector or the like may be engaged with mating threads on the housing1128, as illustrated in FIG. 50.

[0270] As the piston 1142 moves inwardly, because its tapered second end1152 engages the seal 1182 and the seal collapses, the piston 1142 tipsover against the sloped surface 1148 in the enlarged section of the mainpassage 1136. At this time, the top end 1150 of the piston 1142 is nolonger a flat surface with respect to the end of the cannula. Thus,fluid is allowed to freely flow from the tip of the cannula.

[0271] As the piston 1142 moves inwardly, the seal 1182 compresses to aposition in which the branch passage 1138 is in communication with thechamber 1141.

[0272] A fluid path is established from the cannula along the top end1150 of the piston 1142, along the main passage 1136 into the chamber1141, and then into the branch passage 1138. At this time, the fluidvolume within the valve 1120 is an amount V1.

[0273] When the user withdraws the cannula, the seal 1182 presses thepiston 1142 upwardly. The upward movement of the piston 1142 isfacilitated by its engagement with the sloping surface 1148. Eventually,the seal 1182 moves the piston 1142 to the position illustrated in FIG.49. At that time, the seal 1182 again seals the branch passage 1138 fromthe chamber 1141.

[0274] In addition, the seal 1168 seals around the piston 1142,preventing fluid from flowing from the inside of the valve 1120 throughthe main passage 1136 to the first end 1130, thus effecting a positiveflow of fluid.

[0275] As the seal 1182 expands, the volume within the chamber 1141 isreduced, forcing fluid into the branch passage 1138.

[0276] A thirteenth embodiment valve 1220 in accordance with the presentinvention is illustrated in FIGS. 51 and 52. This valve 1220 has astraight-flow arrangement similar to that of the valves illustrated inFIGS. 20-29.

[0277] The valve 1220 has a housing 1228 having a first end 1230 andsecond end 1232. A main passage 1236 extends from the first end 1230 toa smaller extension passage 1238 which extends to the second end 1232.The extension passage 1238 is primarily defined by a wall 1276 which ispositioned within a sleeve 1278.

[0278] A seal 1282 is positioned in a conical portion 1248 of the mainpassage 1236 at the first end 1230. The seal 1282 preferably comprisesfirst and second seal portions which, when put together, form aninverted frusto-conical shaped member. Each seal portion is generallysemi-circular in cross-sectional shape (in a horizontal plane) anddefines a flat inner surface 1283 for engagement with the other sealportion. The outside surface 1185 of each seal portion is curved, andtapers inwardly from top to bottom.

[0279] Each seal portion is biased in a direction towards the second end1232 of the valve 1220. A resilient biasing member 1270 has a first endconnected to a bottom surface of each seal portion and a second endsecured to the housing 1228 some distance along the main passage 1236.As illustrated, each biasing member 1270 comprises a accordion-likeelastic member.

[0280] Operation of the valve 1220 is as follows. When not in use, thebiasing member 1270 corresponding to each portion of the seal 1282biases the seal portions towards the second end 1232 of the valve 1220.In this position, the seal 1282 seals the main passage 1236 at the firstend 1230 of the valve 1220.

[0281] A user inserts a cannula or other medical apparatus, asillustrated in FIG. 52, between the two portions of the seal 1282. Asthe user does this and advances the cannula, the seal portions mustspread apart to accommodate the cannula. This causes the seal portionsto move upwardly towards the first end 1230 of the valve 1220 along theconical surface 1248 against the force of the biasing member 1270.

[0282] Once the cannula is inserted, a fluid path is establishedtherefrom through the main passage 1236 and extension passage 1238through the valve 1230. At this time the fluid volume within the valve1220 is an amount V1.

[0283] When the user withdraws the cannula, the fluid volume in thevalve 1220 reduces to an amount V2, causing fluid to be displacedthrough the extension passage 1238. In particular, once the cannula isremoved, the biasing members 1270 draw the seal portions back towardsthe second end 1232 of the valve 1230 to the position illustrated inFIG. 51. The seal 1282 in this position reseals the main passage 1236 atthe first end 1230 of the valve 1220.

[0284] The valves described above having a seal (182, 282, 382, 482,582, 682, 782, 882, 982, 1082, 1168, 1282) may be adapted for use with aneedle or other implement instead of the blunt cannula 37 illustrated.In this arrangement, the seal may be solid (i.e., not preslit). In thatcase, the piston 142 (or similar member in the later describedembodiments) is preferably constructed of a durable material which isnot ready penetrated by the needle.

[0285] As described above, each valve is preferably provided with ameans for opening and closing a fluid path through the valve. In atleast one embodiment, this means is a moveable piston (ex. piston 42,FIG. 12) while in other embodiments it is a pre-slit seal (ex. seal 182,FIG. 19). Those of skill in the art will appreciate that a variety ofmeans may be provided in addition to those described. For example, aresealable septum or the like may be used.

[0286] In addition, each valve includes a means for decreasing the fluidvolume therein when one of the medical implements is disconnected, forproducing a positive fluid flow. In some embodiments this means is apiston (ex. piston 42, FIG. 12 or piston 1042, FIG. 38) while in otherembodiments it is a resilient member such as a diaphragm or foam-likeelement (ex. element 670, FIG. 28 or element 770, FIG. 30). Those ofskill in the art will appreciate that other means may be provided.

[0287] In some instances, the means for opening and closing the fluidpath is the same as the means for decreasing the fluid volume (ex.piston 42, FIG. 12).

[0288] In the embodiments described above, the fluid space inside thevalve increases upon insertion of a medical implement in the compressedstate and decreases upon withdrawal of the medical implement in thedecompressed state. In some embodiments, the structure defining thefluid space is substantially relaxed and does not store substantialamount of potential energy. Insertion of the medical implement causes achange in the structure that allows it to store potential energy. Thepotential energy is released upon withdrawal of the medical implementand the structure returns to a substantially relaxed condition.

[0289] The above presents a description of the best mode contemplated ofcarrying out the present invention, and of the manner and process ofusing it, in such full, clear, concise, and exact terms as to enable anyperson skilled in the art to which it pertains to make and use thisinvention. This invention is, however, susceptible to modifications andalternate constructions from that discussed above which are fullyequivalent. The embodiments described are meant to be illustrative andnot exhaustive. Consequently, it is not the intention to limit thisinvention to the particular embodiments disclosed. On the contrary, theintention is to cover all modifications and alternate constructionscoming within the spirit and scope of the invention as generallyexpressed by the following claims, which particularly point out anddistinctly claim the subject matter of the invention.

What is claimed is:
 1. A method of effecting a positive flow of fluidthrough a first medical implement automatically upon disconnection of asecond medical implement from a valve having a housing with an elementtherein for controlling the flow of fluid through said housing, saidvalve defining a fluid volume within said housing and said valve incommunication with said first medical implement, comprising the stepsof: disconnecting said second medical implement from said valve; movingat least a portion of said element to a position in which fluid flowthrough said valve to said second medical implement is prevented;decreasing the fluid volume within said valve; and forcing fluid fromsaid housing towards said first medical implement.
 2. The method inaccordance with claim 1 , wherein said element comprises a resilientseal positioned in said housing, said seal having a passage therethroughand wherein said moving step comprises allowing said seal to expand to aposition in which said passage therethrough is occluded.
 3. The methodin accordance with claim 1 , wherein a piston member is movablypositioned within said housing of said valve and said decreasing stepcomprises moving said piston member.
 4. The method in accordance withclaim 3 , wherein said step of disconnecting comprises removing saidfirst medical implement from a first end of said valve, and wherein saiddecreasing step comprises moving said piston towards said first end ofsaid valve.
 5. The method in accordance with claim 1 , wherein a memberis positioned within said housing, said member arranged to increase saidfluid volume in said housing when said first medical implement isconnected to said valve, and wherein said step of decreasing the volumewithin said housing comprises the step of allowing said member to expandin volume.
 6. The method in accordance with claim 1 , wherein a memberis positioned within said housing and cooperates with said housing toform a chamber, and said step of decreasing the volume within saidhousing comprises the step of enlarging the volume of said chamber. 7.The method in accordance with claim 1 , wherein said element comprises aseal, and further including a piston movably positioned within saidvalve, said piston cooperating with said seal and housing to define saidfluid volume, and wherein said step of decreasing the fluid volumecomprises the step of moving said piston towards said seal.